Car won't start? Diagnose it by the sound

Rapid clicking

The starter solenoid is engaging and immediately dropping out because there is not enough current. This is the signature of a discharged battery, and a jump start is the fix. Corroded or loose battery terminals produce the same symptom, so check those first — it costs nothing.

Cranks but never fires

The battery is fine; the engine is turning but not running. That points to fuel delivery, ignition, or the immobiliser. Check the fuel gauge — running out is far more common than people expect, and the gauge can read inaccurately on a slope.

If the security light is flashing, the immobiliser may not be recognising the key. Try the spare key before assuming a mechanical fault.

One loud click, then nothing

The solenoid engaged but the starter motor did not turn. If the lights stay bright, the battery is probably fine and the starter motor is the suspect. This needs a workshop, not a roadside boost.

Complete silence

• Check the vehicle is fully in Park, or the clutch is fully depressed in a manual.
• Check the battery terminals are clean and tight.
• Try the spare key if the vehicle uses a keyless fob — the fob battery may be flat.
• If the dashboard is completely dead, the battery is flat or a main connection has failed.

What roadside assistance can and cannot fix

A roadside driver can boost a flat battery, deliver fuel to an empty tank, and get you into a locked car. A failed starter motor, fuel pump, or ignition fault needs a workshop — no roadside service resolves those on the spot.